What it means
The BMS detects a circuit high fault on voltage sense channel R of the high-voltage battery. Cell-group voltage measurement is unreliable on this channel.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The BMS measures a high-voltage battery cell group through voltage sense channel R. P0B93 sets when the channel R signal is higher than the BMS expects, making that group’s voltage measurement unreliable.
Common causes
Most likely first.
- Sense wire shorted to higher voltage
- Reference regulator overvoltage
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and compare channel R with the other battery voltage readings to determine whether the high signal is persistent or tied to a particular condition.
- With the vehicle powered down as the manufacturer specifies, inspect channel R wiring and connectors for damage, corrosion, or contact with a higher-voltage point.
- Have a qualified hybrid technician check channel R connector seating and pin condition, since poor contact can distort the signal.
- Test the channel R wire for a short to a higher-voltage circuit and check its reference supply according to the manufacturer's procedure and specification.
- If the wiring and reference supply pass, use the manufacturer's diagnostic procedure to determine whether the BMS input or its reference regulator is at fault.
Common fixes
- Repair channel R wiring that is shorted to a higher-voltage circuit.
- Clean or replace corroded or damaged channel R connector terminals.
- Repair a faulty reference supply or regulator if testing confirms overvoltage.
- Repair or replace the BMS component only after wiring and reference checks pass.
Can I keep driving?
Limit driving and avoid charging until the channel R high reading is diagnosed, because the BMS may reduce power or restrict charging when it cannot verify the battery group. Stop safely if the vehicle enters limp mode or power drops.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.